The present invention relates to a mechanical speed governor for a fuel injection pump of air-compressing auto-ignition internal combustion engines, the fuel injection pump having a quantity control member.
In speed governors (so-called RQ governors), it is customary to limit the travel of the quantity control member of the fuel injection pump by stops for the full-load quantity and for the starting quantity. Furthermore, it is customary to provide these speed governors with flyweight arrangements having an adaptation device which effects positive adaptation (reduction of the fuel quantity with increasing speed in the upper speed range).
In a known speed governor, a swivellably designed bracket having a full-load stop can be shifted as a function of the speed from a position corresponding to the starting position to a position corresponding to the full-load position in order to limit the adjustment travel of the quantity control member. In this arrangement, the adaptation device has the task of displacing the quantity control member towards a reduced quantity in the case of high speeds (cf. the publication "Bosch Technische Unterrichtung, Drehzahlregler fur Reheneinspritzpumpen, 1st Edition, Sept. 30, 1975, pages 19 and 38).
A speed governor design of this type permits an adaptation of the delivery characteristic of the injection pump to the fuel requirement characteristic of the internal combustion engine in the upper speed range.
German Patent Document DE-OS 2,838,919 discloses a speed governor for internal combustion engines in which the articulated fork of the quantity control member has a counterstop for the full-load stop of the bracket, and while this counter stop is part of an adaptation device, this design has an expensive construction having a spring-loaded slider corresponding in its positive adaptation effect to that in the flyweights of the flyweight arrangement described earlier.
German Patent Document DE 26 56 261 C2 discloses a speed governor in which, although a full-load stop slides along a stop track, borne by the counterstop, for the negative adaptation, the counterstop is arranged firmly screwed on the governor housing.
An object of the invention is to provide a speed governor, in addition to the positive adaptation, by low-cost constructional measures, with a negative adaptation in the speed range below the positive adaptation. This makes possible improved fitting of the delivery quantity in the entire load range to the fuel requirement of the internal combustion, in particular with the aim of more favorable behavior as regards smoke.
This and other objects are achieved by the present invention which provides a mechanical speed governor for a fuel injection pump of air-compressing, auto-ignition internal combustion engines, the fuel injection pump having a quantity control member, the governor comprising a flyweight arrangement with an adaptation device effecting positive adaptation. The governor includes an articulated fork having a counterstop, this articulated fork being coupled to the quantity control member, and a bracket having a full-load stop. The bracket is shiftable between a starting position corresponding to a starting speed and a full-load position corresponding to a full-load speed such that the full-load stop interacts with the counterstop on the articulated fork. A spring-loaded rocker lever is coupled to the bracket, this rocker lever shifting the bracket between the starting position and the full-load position as a function of speed. The counterstop includes a stop track on which the full-load stop slides as a function of speed, this stop track effecting a negative adaptation.
The present invention provides a counterstop fixed to the articulated fork only with one, special stop track, which does not impair the releasing or enabling of the starting quantity, along which the full-load stop of the swivellable bracket slides under speed control. By this design, an adaptation is provided which is negative in the lower speed range and operates independently of the positive adaptation acting in the upper speed range. Also, the behavior of the internal combustion engine is considerably improved with respect to smoke in a relatively simple manner.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.